Electric lamp holders

ABSTRACT

An electric lamp holder comprises an electric lamp support and a housing therefor. The housing is of cylindrical form, one end and an adjacent cylindrical wall portion of the housing being of glass, and the remainder of the housing being of a metal having a coefficient of expansion which is substantially the same as that of the glass. Electrical connection to the electric lamp carried by the support is provided by a pair of resilient electrical contacts extending through the glass end wall of the housing. A plurality of these holders are mounted within a casing of a pressurized indicating instrument to illuminate from the rear a display face of the instrument. The housings are air-tight and are mounted in apertures in the casing, air-tight seals being provided between the housings and the instrument casing so as to enable the electric lamps to be replaced without depressurizing the instrument.

United States Patent 1 1 Evans et a1.

154] ELECTRIC LAMP HOLDERS [75] Inventors: William Henry Reginald Evans;

John Richard Burgess, both of Cheltenham, England [73] Assignee: Smiths Industries Limited, London,

' England [22] Filed: July 7, 1971 [21] Appl. No.: 160,471

[30] Foreign Application Priority Data,

July 10, 1970 Great Britain ..33,563/70 Nov. 10, 1970 Great Britain ..53,351/7O [51] Int, Cl. ..'...;G0ld 11/28 [58] Field of Search. ..240/2.1, 8.16;

[56] References Cited UNITED STATES PATENTS 2,823,299 2/1958 Squire et a1. ..240/8. 16

3,629,568 12/1971 Hanes... ..240/2 1 3,604,918 9/1971 Cook.... 240/8.16

3,440,647 4/1969 Sloan 340/381 3,320,412 5/1967 l-lowland ..240/2.1

- I9 25 f6 f7 1 1r I /'/r Apr. 10, 1973 3,602,708 8/1971 Dupree; ..240/8.16

FOREIGN PATENTS OR APPLICATIONS 690,168 7/1964 Canada ..240/2.1

Primary Examiner-Joseph F. Peters, Jr. Attorney-William D. Hall et a1.

57 1 ABSTRACT An electric lamp holder comprises an electric lamp support and a housing therefor. The housing is of cylindrical form, one end and an adjacent cylindrical wall portion of the housing being of glass, and the remainder of the housing being of a metal having a coefiicient of expansion which is substantially the same as that of the glass. Electrical connection to the electric lamp carried by the support is provided by a pair of resilient electrical contacts extending through the glass end wall of the housing. A plurality of these holders are mounted within a casing of a pressurized indicating instrument to illuminate from the rear a display face of the instrument. The housings are air-tight and are mounted in apertures in the casing, air-tight seals being provided between the housings and the instrument casing so as to' enable the electric lamps to I ELECTRIC LAMP HOLDERS This invention relates to electric lamp holders. According to one aspect of the present invention there is provided an electric lamp holder comprising a 2 within the housing both an electric lamp and the pair of electrical contacts, the housing comprising a first wall section of opaque material, and a second wall section integral with the first wall section and of light transmitting material for transmitting light-rays from an electric lamp disposed within the housing, and a second pair of electrical contacts which extend through the wall of the housing and which are arranged resiliently to engage respective ones of the first electrical contacts, there being an air-tight seal between the first and second wall sections, and between the wallof the housing and the second pair of electrical contacts.

Preferably the housing is in the form of a cylinder which is closed at one end and which at its other end includes the said housing aperture, the said second wall section being constituted by the said closed end and a cylindrical wall portion of the cylinder adjacent thereto, and the said first wall section being constituted by the remaining cylindrical wall portion and the said other end of the cylinder.

The said first wall section may be of metal and the said second wall section may be of glass, and, in such a case, the metal may have a coefficient of expansion which is substantially the same as that of the glass.

At leastthe part of the cylindrical wall portion of metal immediately adjacent to the cylindrical wall portion of glass may have a wall thickness which is substantially less than the wall thickness of the cylindrical wall portion of glass. I

The said first wall section may be fused to the said second wall section.

The support member may include a tube, and, in such a case, the first pair of electrical contacts are constituted by a pair of slip-rings mounted on the exterior ofthe tube and spaced apart axially thereof.

The housing aperture may be screw-threaded and, in this case, the support member may include a cap having a screw-thread which co-operates with the screwthreaded aperture to mount the support member in the housing.

According to a further aspect of the present invention,.there is provided an indicating instrument comprising a casing which is arranged to be pressurized and a plurality of electric lamp holders as aforesaid which are arranged to carry electric lamps for illuminating a display face of the instrument, the housings of the ho]- ders being mounted in respective apertures in the casing, and air-tight seals being provided between the I housings and the casing.

The said first wall sections of the housings may be of metal, and, in such a case, the air-tight seals between the housings and the casing may be constituted by metal joints between the casing and the respective first wall sections.

A pressure indicating instrument incorporating various forms of electric lamp holder, in accordance with the present invention, for illuminating a dial of the instrument from the rear, will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a front elevation of the instrument;

FIG. 2 is a fragmentary sectional view on the line llll of FIG. 1 showing one form of electric lamp holder;

FIG. 3 is a fragmentary sectional view of the instrument showing an alternative form of the electric lamp holder; and

FIG. 4 is a fragmentary sectional view on the line IVlV of FIG. 3.

Referring to FIGS. 1 and 2 of the drawings, the instrument includes a rectangular metal case 10 having a peripheral mounting flange 11. The case 10 includes a front-panel 12 having a central, circular aperture 13 in which is mounted a glass window 14. The annular space between the front-panel l2 and the window 14 is sealed by a resilient ring 42 of inverted U-shape in cross-section, one wall of the ring 42 resiliently bearing against the peripheral edge of the window 14 while the other wall of the ring 42 resiliently bears against the edge of the front panel 12 bounding the aperture 13. The metal case 10 and the glass-window 14 together constitute an air-tight casing of the instrument. The temperature of the instrument will vary considerably during use, because the metal case 10 and the glass window 14 have widely different coefficients of expansion, the consequent variation in width of the annular space between the window 14 and the front-panel 12 could be sufficient to break the glass window 14. However, since the ring 42 is of U-shape in cross-section, the ring 42, in addition to providing an airtight seal in the space between the window 14 and the front-panel 12, will also flex with changes in the width of the annular space and thereby reduce the likelihood of breakage of the window 14.

The case 10 houses a disc 15 (shown in FIG. 2) which is of transparent plastic material (for example that sold under the trademark Perspex) and is spaced from and extends parallel to the window 14. The front of the disc 15 has a central, circular hole 16 formed therein whose depth is approximately equal to onethird of the thickness of the disc 15. The circumferential edge of the hole 16 is stepped at 17 so that the portion of the hole 16 lying adjacent the front of the disc 15 is of slightly larger diameter than the remainder of the hole 16. A translucent dial 18, having a thickness less than the depth of the portion of the hole 16 of smaller diameter, is mounted in the bottom of the hole 16. A pointer (not shown) is mounted within the'portion of the hole 16 of larger diameter, by a spindle extending through an axial hole in the disc 15. At the front of the disc 15 the outer circumferential edge has a bevelled surface 19 which is inclined at an angle of forty-five degrees to the front of the disc 15. A tapered, circular hole 20 is formed in the rear of the disc 15. The hole 20 has a maximum diameter which is slightly less than the diameter of the disc 15 and the degree of taper of the hole 20 is selected so that the circumferential edge of the hole 20 extends parallel to the bevelled surface 19. An annular, masking ring 21 is clamped between the window 14 and the disc 15.

In order to illuminate the dial 18 from the rear and to illuminate the pointer, the front-panel 12 carries, at each corner, a pair of electric lamp holders 22. One such electric lamp holder 22 is shown in detail in FIG. 2 and comprises a housing 23 and an electric lamp support 24 disposed within the housing 23. The housing 23 is of tubular construction and is supported at one end in an aperture in the front-panel 12, the housing 23 extending rearwardly in the instrument case just beyond the disc 15. The front portion of the housing 23 is constituted by a metal sleeve 25 and the remainder of the housing 23 is constituted by a glass envelope 26 which is fused to the metal sleeve 25 and has an endwall which closes the rear-end of the housing 23. The metal sleeve 25 has a portion 27 of increased thickness disposed within the aperture in the front-panel 12. The portion 27 has an outer circumferential flange 28 which abuts a shoulder 29 within the aperture in the front-panel 12 and which is welded at 30 to the front panel 12. This weld extends completely round the flange 28 so as to provide an airtight seal between the housing 23 and the front panel 12. The sleeve 25 is of a nickel-alloy material having a coefficient of expansion which is substantially the same as that of the glass used in the envelope 26.

The electric lamp support 24 is of plastic material and comprises a tube 31, which at its rear end carries an electrical lamp 32, and a screw-threaded cap 33 which is disposed at the other end of the tube 31 and which co-operates with a screw-threaded aperture in the portion 27 to mount the lamp 32 within the glass envelope 26. The tube 31 carries in its outer circumferential surface a pair of axially-spaced slip-rings 34 of brass which are moulded as inserts in the tube 31. The slip-rings 34 are electrically connected to wires 35 which extend from the base of the lamp 32 and are electrically connected to the lamp filament. To this end, the tube 31 has a pair of grooves 36 in its external surface, the grooves 36 being axially spaced between the slip-rings 34 and disposed adjacent to the edges of respective ones of the slip-rings 34. The grooves 36 communicate with the bore of the tube 31 through respective holes 37. In order to effect the electrical connection, the wires 35 are inserted into the bore of the tube 31 and then outwardly through the respective holes 37, the wires 35 then being bent round the tubular portion 31 within the grooves 36 and soldered to the slip-rings 34. By such an arrangement the wires 35, in addition to providing the electrical connections between the lamp 32 and the slip-rings 34, also serve to mount the lamp 32 on the rear-end of the tube 31.

The electrical supply to the lamp 32 is effected through a pair of resilient arms 38 which engage respective slip-rings 34 when the electric lamp support 24 is mounted in the housing 23. The arms 38 are conveniently of phosphor bronze wire and extend through metal tubes 39 fused into the end wall of the glass envelope 26. The arms 38 are soldered into the metal tubes 39 to provide an air-tight seal between the arms 38 and the tubes 39.

When the lamps 32 are energized the light rays emitted there-from pass through the envelope 26 and into the disc to illuminate the dial l8 and also the pointer mounted on the disc 15. This latter illumination is effected by those light-rays which enter the disc 15 normal to its circumferential edge and strike the circumferential edge of the hole 20. Such a light-ray is represented by a dotted line 40. These light-rays, after reflection at the circumferential edge of the hole 20, are reflected at the bevelled surface 19 and pass into the hole 16 to illuminate the pointer. In order to prevent flare on the dial 18 it is desirable to prevent any light-rays striking the face of the dial 18. This is achieved by painting the circumferential edge of the portion of the hole 16 of reduced diameter.

A sealing washer 41 is provided between the cap 33 and the flange 28 to prevent ingress of moisture into the housing 23.

An alternative form of lamp support 24 is shown in FIGS. 3 and 4. For simplicity, instrument components common to both FIGS. 2 and 3 have been designated with the same reference numerals. Referring to FIGS. 3 and 4, the lamp support 124 in this arrangement comprises a tube 131, which at its rear end is shaped to provide a seating for the electric lamp 32, and a screwthreaded cap 133 mounted on the other end of the tube 131. To this end, the cap 133 carries a pin 134 which projects into a longitudinal hole 135 in the tube 131 and is secured therein by an epoxy resin adhesive. The cap 133 cooperates with a screw-threaded aperture in the portion 27 of the housing 23 to mount the lamp 32 within the glass envelope 26. The end of the tube 131 adjacent to the cap 133 has formed therein a pair of slots 136 and 137 (FIG. 4) which extend transversely of the tube 131 at right angles to one another. A pair of diametrically-opposed longitudinal slots 138 and 139 are formed in the inner circumferential surface of the tube in alignment with the slot 136. The tube 131 carries in its outer circumferential surface a pair of contact-rings 140 for electrical connection to the lamp 32. The contact-rings 140 are connected to respective electric cables 141 and 143. The contact-rings 140 and the electric cables 141 and 143 are, after appropriate electrical connection, moulded as inserts in the tube 131 so that the ends of the cables 141 and 143 remote from the contact-rings 140 extend into the slot 137 on opposite sides of the longitudinal hole 135. These ends of the cables 141 and 143 are then bent to extend radially outwards in the slot 137 and round respective parts of the outer circumferential surface of the tube 131 in an anti-clockwise direction as shown in FIG. 4. In order to effect the electrical connection between the electric lamp 32 and the contact-rings 140, the electric lamp 32 is flrstly secured to the rear-end of the tube 131 by an epoxy resin adhesive, with its electric leads 144 and 145 extending through the slots 138 and 139 respectively into the transverse slot 136. The ends of the leads 144 and 145 are then bent to extend radially outwards in the slot 136 and round the outer circumferential surface of the tube 131 in a clockwise direction to abut the ends of the cables 143 and 141 respectively, and, finally, the abutting ends of the cables 141 and 143, and the leads 144 and 145 are soldered to one another. The electric lamp 32 is mounted on the tube 131 and the electrical connections between the lamp 32 and the contact-rings 140 are established prior to mounting the cap 133 on the tube 131..

The electrical supply for the lamp 32 is connected to a pair of resilient arms 146 which engage respective contact-rings 140 when the electric lamp support 124 is mounted in the housing 23.

The portions of the housings 23 disposed within the case each constitute an air-tight assembly and, therefore, it is possible to withdraw the lamp supports 24 from the housings 23 to facilitate replacement of the electric lamps 32 without depressurizing the indicating instrument.

As previously mentioned, the temperature of the case 10 will vary considerably during use and it is necessary, therefore, to ensure that this change in temperature will not cause the glass envelopes 26 to fracture. This is achieved by arranging that the lengths of the sleeves 25 between their portions 27 and the glass envelopes 26 have a wall thickness which is very much smaller than the wall thickness of the glass envelopes 26, so that any strain caused by differential expansion of the case 10 and the sleeves 25 is substantially confined to the thin-walled lengths of the sleeves 25.

Although the electric lamp holders 22 have been described with reference to pressurized indicating instruments, it is visualized that the electric lamp holders 22 may, if desired, also be used on unpressurized in dicating instruments.

We claim:

1. An indicating instrument comprising:

a. a casing;

b. display means mounted in the casing;

c. means for illuminating said display means within the casing, said illuminating means comprising an electric lamp holder mounted to extend into the casing from outside thereof, said lamp holder comprising i. a member for supporting an electric lightemitting lamp,

ii. a pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member,

iii. a lamp housing having an aperture therein for receiving the support member with the lamp and said contacts located wholly within the housing, said housing comprising an end-part defining said aperture, an opaque wall section integral with said end part, a light-transmitting wall section extending from said opaque wall section for transmitting said light through the housing wall, and means for providing an air-tight seal between the opaque and light-transmitting wall sections,

- iv. a pair of electrical leads that extend through the said light-transmitting wall section of the housing for resiliently engaging respective ones of the said contacts, and

v. an air-tight seal between the wall of the housing and the said electrical leads; and

d. means'sealing the said end-part of the lamp-holder housing to the casing with said opaque and lighttransmitting wall sections projecting into the cas- 2. An electric lamp holder comprising: a member for supporting an electric light-emitting lamp; a first pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member; a cylindrical lamp-housing having an aperture therein for receiving the support member with the lamp and said first pair of contacts located wholly within the housing,

said housing comprising a first end-part defining said aperture for receiving said support member as aforesaid and adapted to co-operate with said support member for retention of said support member in said aperture, and a cylindrical wall which extends from said first end-part for embracing the lamp within the housing and which includes a second end-part at the opposite end of the housing from said first end-part to close the housing at that end, said housing having an opaque section constituted by a portion of the said wall extending from said first end-part, a light-transmitting section constituted by the remainder of the wall for transmitting said light through the housing wall, and a first air-tight seal sealing said light-transmitting section to said opaque section; a second pair of electrical contacts that extend through the said wall of the housing for resiliently engaging respective ones of the said first pair of electrical contacts; and a second air-tight seal between the wall of the housing and the second pair of electrical contacts.

3. A holder according to claim 2, wherein the said second pair of electrical contacts extend through the said end-part of said housing.

4. A holder according to claim 2, including a pair of spaced metal sleeves carried by the housing to extend through said wall, and wherein respective ones of the said second pair of electrical contacts extend through said sleeves and are soldered therein.

5. A holder according to claim 2, wherein the said opaque section is of metal and the said light-transmitting section is of glass, the metal having a coefficient of expansion which is substantially the same as that of the glass.

6. A holder according to claim 5, wherein the said opaque section is fused to the said light-transmitting section. 1

7. A holder according to claim 2, wherein the said opaque section is of metal and the said light-transmitting section is of glass, and wherein at least the part of the said opaque section immediately adjacent to the said light-transmitting section has a wall thickness which is substantially less than that of the said lighttransmitting section.

8. A holder according to claim 2, wherein the said support member includes a tube, and wherein the said first pair of electrical contacts are constituted by a pair of slip-rings mounted on the exterior of the tube and spaced apart axially thereof.

9. A holder according to claim 2, wherein the said housing aperture is screw-threaded, and wherein the said support member includes a cap having a screwthread for co-operating .with the said screw-threaded aperture to mount the support member in the housing.

10. An indicating instrument comprising:

a. an air-tight casing;

b. display means sealed into the casing;

c. means for illuminating said display means within the casing, said illuminating means comprising a plurality of electric lamp holders mounted to extend into the casing from outside thereof and each lamp holder comprising i. a member for supporting an electric lightemitting lamp, ii. a first pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member,

iii. a cylindrical lamp-housing having an aperture therein for receiving the support member with the lamp and said first pair of contacts located wholly within the housing, said housing comprising a first end-part defining said aperture for receiving said support member as aforesaid and adapted to co-operate with said support member for retention of said support member in said aperture, and a cylindrical wall extending from said first end-part for embracing the lamp within the housing, said wall including a second endpart at the opposite end of the housing from said first end-part to close the housing at that end, said housing having an opaque section constituted by a portion of the said wall extending from said first end-part, a light-transmitting section constituted by the remainder of the wall for transmitting said light through the housing wall, and a first air-tight seal sealing said light-transmitting section to said opaque section,

iv. a second pair of electrical contacts that extend through the said wall of the housing for resiliently engaging respective ones of the said first pair of electrical contacts, and

v. a second air-tight seal between the wall of the housing and the second pair of electrical contacts; and

d. air-tight sealing means sealing the said housings of the said lamp holders into the casing.

11. An instrument according to claim 10, wherein the said opaque sections of the housings are of metal, and wherein the air-tight seals between the housings and the casings are constituted by metal joints between the casing and the respective said opaque sections.

12. An instrument according to claim 10, wherein the said casing includes a front panel, and wherein the front panel has apertures therein to receive said lamp holders respectively. 

1. An indicating instrument comprising: a. a casing; b. display means mounted in the casing; c. means for illuminating said display means within the casing, said illuminating means comprising an electric lamp holder mounted to extend into the casing from outside thereof, said lamp holder comprising i. a member for supporting an electric light-emitting lamp, ii. a pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member, iii. a lamp housing having an aperture therein for receiving the support member with the lamp and said contacts located wholly within the housing, said housing comprising an end-part defining said aperture, an opaque wall section integral with said end part, a light-transmitting wall section extending from said opaque wall section for transmitting said light through the housing wall, and means for providing an air-tight seal between the opaque and light-transmitting wall sections, iv. a pair of electrical leads that extend through the said light-transmitting wall section of the housing for resiliently engaging respective ones of the said contacts, and v. an air-tight seal between the wall of the housing and the said electrical leads; and d. means sealing the said end-part of the lamp-holder housing to the casing with said opaque and light-transmitting wall sections projecting into the casing.
 2. An electric lamp holder comprising: a member for supporting an electric light-emitting lamp; a first pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member; a cylindrical lamp-housing having an aperture therein for receiving the support member with the lamp and said first pair of contacts located wholly within the housing, said housing comprising a first end-part defining said aperture for receiving said support member as aforesaid and adapted to co-operate with said support member for retention of said support member in said aperture, and a cylindrical wall which extends from said first end-part for embracing the lamp within the housing and which includes a second end-part at the opposite end of the housing from said first end-part to close the housing at that end, said housing having an opaque section constituted by a portion of the said wall extending from said first end-part, a light-transmitting section constituted by the remainder of the wall for transmitting said light through the housing wall, and a first air-tight seal sealing said light-transmitting section to said opaque section; a second pair of electrical contacts that extend through the said wall of the housing for resiliently engaging respective ones of the said first pair of electrical contacts; and a second air-tight seal between the wall of the housing and the second pair of electrical contacts.
 3. A holder according to claim 2, wherein the said second pair of electrical contacts extend through the said end-part of said housing.
 4. A holder according to claim 2, including a pair of spaced metal sleeves carried by the housing to extend through said wall, and wherein respective ones of the said second pair of electrical contacts extend through said sleeves and are soldered therein.
 5. A holder according to claim 2, wherein the said opaque section is of metal and the said light-transmitting section is of glass, the metal having a coefficient of expansion which is substantially the same as that of the glass.
 6. A holder according to claim 5, wherein the said opaque section is fused to the said light-transmitting section.
 7. A holder according to cLaim 2, wherein the said opaque section is of metal and the said light-transmitting section is of glass, and wherein at least the part of the said opaque section immediately adjacent to the said light-transmitting section has a wall thickness which is substantially less than that of the said light-transmitting section.
 8. A holder according to claim 2, wherein the said support member includes a tube, and wherein the said first pair of electrical contacts are constituted by a pair of slip-rings mounted on the exterior of the tube and spaced apart axially thereof.
 9. A holder according to claim 2, wherein the said housing aperture is screw-threaded, and wherein the said support member includes a cap having a screw-thread for co-operating with the said screw-threaded aperture to mount the support member in the housing.
 10. An indicating instrument comprising: a. an air-tight casing; b. display means sealed into the casing; c. means for illuminating said display means within the casing, said illuminating means comprising a plurality of electric lamp holders mounted to extend into the casing from outside thereof and each lamp holder comprising i. a member for supporting an electric light-emitting lamp, ii. a first pair of electrical contacts mounted on the support member for connection to respective electrical terminals of the electric lamp carried by said support member, iii. a cylindrical lamp-housing having an aperture therein for receiving the support member with the lamp and said first pair of contacts located wholly within the housing, said housing comprising a first end-part defining said aperture for receiving said support member as aforesaid and adapted to co-operate with said support member for retention of said support member in said aperture, and a cylindrical wall extending from said first end-part for embracing the lamp within the housing, said wall including a second end-part at the opposite end of the housing from said first end-part to close the housing at that end, said housing having an opaque section constituted by a portion of the said wall extending from said first end-part, a light-transmitting section constituted by the remainder of the wall for transmitting said light through the housing wall, and a first air-tight seal sealing said light-transmitting section to said opaque section, iv. a second pair of electrical contacts that extend through the said wall of the housing for resiliently engaging respective ones of the said first pair of electrical contacts, and v. a second air-tight seal between the wall of the housing and the second pair of electrical contacts; and d. air-tight sealing means sealing the said housings of the said lamp holders into the casing.
 11. An instrument according to claim 10, wherein the said opaque sections of the housings are of metal, and wherein the air-tight seals between the housings and the casings are constituted by metal joints between the casing and the respective said opaque sections.
 12. An instrument according to claim 10, wherein the said casing includes a front panel, and wherein the front panel has apertures therein to receive said lamp holders respectively. 